Steel Button Joining of Aluminum to Steel by Spot Welding
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Solution Overview
Problem
Current methods for joining different materials, such as steel and aluminum, fail to achieve high joining strength while maintaining cost-effectiveness, particularly in vehicle body components.
Innovation Solution
A joining method involving a button component with a T-shaped cross section made of steel, where the tapered end is pushed into an aluminum plate without heating and then welded to a steel plate using resistance spot welding, applying a higher pressure initially and a lower pressure during welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional joining methods (rivet pushing through aluminum plate and welding to steel plate) are used, then joining of dissimilar materials is achieved, but joining strength is insufficient
Solution Approach 1:
The button component serves as an intermediary element between the aluminum plate and steel plate. It includes an aluminum alloy portion that bonds to the aluminum plate and a steel portion that welds to the steel plate, creating a three-material joining system that overcomes the limitations of direct dissimilar material joining
Solution Approach 2:
The button component is constructed as a composite structure with different material portions (aluminum alloy and steel) connected together. This composite design allows each portion to be optimally matched with its corresponding base material, achieving superior joining strength
2Ease of manufacture
If high pressure is applied to push the button component through the aluminum plate, then insertion is achieved, but the button component may deform or lose strength
Solution Approach 1:
The button component is pre-formed with a tapered shape and predetermined geometry that facilitates easy insertion through the aluminum plate. The preliminary shaping allows the component to be pushed through with appropriate pressure without requiring additional forming operations that could compromise strength
Solution Approach 2:
The button component has different geometric properties at different locations - a tapered distal end for insertion and a structured body for strength. This local variation in geometry allows easy insertion at the tip while maintaining overall structural integrity
3Strength
If resistance spot welding is used to join the button component to the steel plate, then strong welding is achieved, but welding parameters must be precisely controlled
Solution Approach 1:
The steel portion of the button component has specific material properties (tensile strength 400-1500 MPa) that are optimized for resistance spot welding. These parameter specifications ensure reliable welding while allowing for standard welding processes to be used
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method achieves a high joining strength between dissimilar metal materials without increasing manufacturing costs, as evidenced by the formation of a strong nugget between the button component and the steel plate, while preventing strength reduction in the button component.
Implementation Method 1
welding the distal end of the button component and the first component by resistance spot welding
Data Source
AI summary
An aluminum plate (103) is overlaid on a steel plate (102). A distal end (113) of a button component (101) is pushed in from the obverse surface side of the aluminum plate (103), and the distal end (113) is abutted against the steel plate (102) by applying a first pressure to the button component (101) made of steel without heating. The distal end (113) of the button component (101) and the steel plate (102) are welded by resistance spot welding while applying a second pressure lower than the first pressure to the button component (101).